This invention relates to apparatus for forming field seams in single ply roofing membranes. When installing a roof on a flat roof building, roof membranes are applied over a base structure, which is typically a concrete substrate, covered by an insulation board. Roof membranes, which are made of polymeric materials, such as ethylene propylene diene monomer (EPDM), repel water and snow and generally protect the integrity of the underlying structure. Use of EPDM membranes is preferred because, being unsaturated, degradation due to sunlight and ozone is greatly diminished.
It is necessary to secure the membrane to the roof to prevent movement as well as actual lifting when high winds pass over the roof. In some installations roofing membranes are held down on the roof with a layer of river rock. Because this adds considerably to the weight of the roof, another method of securement is by the use of an adhesive. Mechanical fasteners are not suitable because their use would perforate the membrane, creating a breach in the integrity and seal of the roof. One method of application utilizes fasteners that pass through a narrow width of a scrim reinforced membrane, through the insulation and into the concrete or other substrate. The latter membrane is applied to the roof in strips across the roof at periodic intervals, on the order of eight feet (2.4 M). Then the single ply roofing membrane is applied to these strips with the use of adhesive, thereby securing the roofing membrane to the roof at eight foot (2.4 M) intervals.
The roofing membranes are typically manufactured in wide sheets, on the order of 10 to 50 feet (3 to 15 M) wide and are produced in lengths sufficient to cover the length or width dimension of a building roof without splicing. Where a dimension, such as the width, exceeds the width of the membrane, successive sheets are spliced together. Seams, when necessary, must also ensure weatherability and watertightness of the roof. In both instances, splicing and joining the overlying membrane to the strips, it is necessary to adhere overlapping sheets together, in the case of splicing, and to adhere the single ply membrane to the strip in the latter instance. This is done by the application of an adhesive, in the form of a liquid or tape containing a pressure-sensitive adhesive, to the mating surfaces, and then applying pressure to the mating surfaces to obtain adhesion, typically by rolling the surfaces.
At present, the two types of joints are made with the aid of a hand roller, operated by a worker, on his hands and knees, moving the roller in a back and forth motion over a small area and progressing forward to the edge of the roof. In addition to the labor involved, the seaming is not always uniform due to differences in application forces from worker to worker as well as the fatigue of the worker after prolonged seaming. An apparatus that minimizes fatigue and ensures a more uniform application force is desired.